1. Department of Agriculture and Animal Health, College of Agriculture and Environmental Sciences, University of South Africa, Private Bag X6, Florida 1710, South Africa
2. Agricultural Research Council-Tropical and Subtropical Crops, Private Bag X11208, Mbombela 1200, South Africa
3. Agricultural Research Council-Plant Health and Protection, Private Bag X134, Queenswood 0121, South Africa
4. Department of Zoology, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg 2006, South Africa
5. School of Agricultural, Earth and Environmental Sciences, University of Kwa-Zulu Natal, Cabbis Road, Scottsville, Pietermaritzburg 3201, South Africa
6. Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa
7. Laboratory of Tropical Crop Improvement, Department of Biosystems, Faculty of Bioscience Engineering, University of Leuven (KU Leuven), Willem de Croylaan 42, 3001 Heverlee, Belgium